Uniswap 4.0

Notable features:

• A time-weighted average market maker
• Singleton Design
• Hooks
• Non Upgradeable
• Onchain limit orders
• Depositing out-of-range liquidity into lending protocols
• Autocompounded LP fees back into the LP positions
• Better Gas optimization
• Customizable
• Developer friendly
• Super Generic

Uniswap V3 Context

Uniswap V4

PoolManager Contract:

Contract Inheritance:

• Inherits from IPoolManager, Fees, NoDelegateCall, and Claims.

Constants:

• MAX_TICK_SPACING and MIN_TICK_SPACING used for valid tick spacing in pools.

State Variables:

• currencyDelta: Tracks net currency amounts for lockers.
• reservesOf: Tracks currency reserves.
• pools: Mapping of pool IDs to their states.

Constructor:

• Initializes with a gas limit for the controller, passed to Fees.

Pool Management Functions:

• _getPool: Private function to retrieve pool state.
• initialize: Sets up a pool with parameters, checks validity, and calls hook functions if defined.
• lock: Allows locker actions, settles currency balances at lock end.
• modifyPosition: Adjusts liquidity, handles fees for LPs.
• swap: Executes token swaps within a pool, updates balances and fees.
• donate: Adds liquidity to a pool without receiving tokens.
• take, settle, mint, burn: Manage pool reserves and balances.

Fee Management:

• Functions to update protocol, hook, and swap fees.

External Storage Loading:

• Functions extsload read storage slots directly for off-chain use.

Locking Mechanism:

• Manages and queries the locking mechanism to ensure atomic actions.

Fallback Function:

• receive function to accept native tokens for relevant pools.

Security Considerations:

• Uses noDelegateCall modifier to prevent delegate calls.
• Locking mechanism prevents reentrancy with onlyByLocker modifier.
• Uses unchecked blocks for arithmetic (be cautious of overflow/underflow).
• Hooks and callbacks add complexity; return values are checked for expected selectors.
• initialize prevents invalid pool configurations.
• Emits events for transparency and off-chain monitoring.

State-Changing Functions in PoolManager Contract

• initialize: Initializes a pool, potentially changing state variables.
• lock: Allows locker actions, settles currency balances at the end, altering state.
• _accountDelta: Potentially modifies account currency deltas.
• _accountPoolBalanceDelta: Alters account pool balance deltas, affecting state.
• modifyPosition: Changes liquidity provider positions, adjusts liquidity, handles fees.
• swap: Executes token swaps within a pool, updating balances and fees, affecting state.
• donate: Adds liquidity to a pool without receiving tokens, potentially altering state.
• take, settle, mint, burn: Manage pool reserves and balances, changing the state.
• setProtocolFees: Updates protocol fees, potentially changing contract behavior.
• setHookFees: Alters hook fees, potentially impacting transaction fees.
• updateDynamicSwapFee: Updates dynamic swap fees for trades, affecting state.

Additional State Change:

• receive Function: Receives native tokens (e.g., ETH), changing the contract's balance.

Fees Contract Overview

Constants and State Variables:

• MIN_PROTOCOL_FEE_DENOMINATOR: Sets the minimum denominator for protocol fees.
• MAX_SWAP_FEE: Defines the maximum allowed swap fee.
• protocolFeesAccrued: Tracks accrued protocol fees per currency.
• hookFeesAccrued: Tracks accrued hook fees per currency and hook address.
• protocolFeeController: Manages protocol fees.
• controllerGasLimit: Immutable gas limit for calls to the protocol fee controller.

Constructor:

• Sets controllerGasLimit on contract deployment.

Fee Fetching Functions:

• _fetchProtocolFees: Retrieves protocol fees for a pool, performs gas checks, and validates fees.
• _fetchHookFees: Retrieves hook fees for a pool based on mask and hook conditions.
• _fetchDynamicSwapFee: Retrieves dynamic swap fee for a pool, reverts if fee is too large.

Fee Checking Function:

• _checkProtocolFee: Ensures fee is not below MIN_PROTOCOL_FEE_DENOMINATOR unless zero.

Protocol Fee Controller Management:

• setProtocolFeeController: Allows owner to set the protocol fee controller.

Fee Collection Functions:

• collectProtocolFees: Allows owner or protocol fee controller to collect accrued protocol fees for a currency.
• collectHookFees: Allows a hook to collect accrued hook fees for a currency.

Security Considerations:

• Uses Solidity ^0.8.x with built-in overflow checks, reducing arithmetic vulnerabilities.
• try/catch blocks in fee-fetching functions prevent revert on external call failure, but may cause unexpected behavior.
• controllerGasLimit must be carefully set to avoid EIP-150's 63/64 rule causing out-of-gas errors.
• collectProtocolFees and collectHookFees have checks for authorized addresses, promoting security.
• collectHookFees allowing recipient set to hook address for zero address could be a feature or potential vulnerability.
• Emits an event when protocol fee controller updates, enhancing transparency.
• Incomplete implementation of IFees interface due to abstract nature. Full implementation review necessary for security.

Overall, while the contract structure seems robust, a thorough security audit should encompass all external contracts, libraries, and system-wide checks for vulnerabilities or logical errors.

State-Changing Functions

setProtocolFeeController(IProtocolFeeController controller):

• Sets the protocol fee controller to a new address.
• Accessible only by the owner of the contract.

collectProtocolFees(address recipient, Currency currency, uint256 amount):

• Collects accrued protocol fees for a given currency and transfers them to a specified recipient.
• Accessible by the owner or the protocol fee controller.

collectHookFees(address recipient, Currency currency, uint256 amount):

• Collects accrued hook fees for a given currency and transfers them to a specified recipient.
• Accessible by any hook address that has accrued fees.

Claims Contract Functionality

• balances: Private mapping tracking each account's currency balance.
• balanceOf: Public view function returning the balance of a specified currency for an account.
• transfer: Public function allowing currency transfer between accounts after checking recipient and sender conditions. Deducts from sender and adds to recipient, emitting a Transfer event.
• _mint: Internal function increasing currency balance for an account and emitting a Mint event, callable only within the contract or derived contracts.
• _burn: Internal function decreasing currency balance for the message sender and emitting a Burn event, provided sender has sufficient balance.

Security Considerations:

• transfer function lacks zero address check for the recipient but prevents sending to the contract's address, potentially a design choice.
• Uses unchecked block in transfer function for balance subtraction after ensuring sufficient balance, optimizing gas.
• _mint and _burn are internal, accessible only to the contract or derived contracts, preventing external minting/burning.
• No access control for _mint function, advisable to restrict minting privileges for security.
• Emits events for Transfer, Mint, and Burn operations, enhancing transparency.
• The use of a custom Currency type and its associated library could impact contract security, warranting a thorough review.
• Non-compliance with ERC-20 standard might affect compatibility with wallets/interfaces.
• Specifies BUSL-1.1 license, impacting legal compliance and usage terms.

Overall, the contract seems a basic implementation of a multi-currency token system. However, a comprehensive security audit should cover Currency type, CurrencyLibrary, IClaims interface, and other interacting contracts. Also, context like governance mechanisms and administrative functions influencing minting/burning should be considered.

State-Changing Functions in Claims Contract:

• transfer: Modifies the balances mapping by transferring a specified amount of currency from the sender to the recipient.
• _mint: Increases the balance of a particular currency for a specified address in the balances mapping.
• _burn: Decreases the balance of a specific currency for the message sender in the balances mapping.

Note:

• You can get these images here:
• https://github.com/Nepalichhoro/big-hustler-defi-hub

References:

https://www.youtube.com/watch?v=iILNV4YFGdk